<!DOCTYPE html>
<html>

<head>
	<meta charset="utf-8">
	<title>三栏布局</title>
	<style type="text/css">
		.wrapper {
			display: flex;
		}

		.left {
			width: 200px;
			height: 300px;
			background: lightblue;
		}

		.middle {
			width: 100%;
			background: #FFAAFF;
			margin: 0 20px;
		}

		.right {
			width: 200px;
			height: 400px;
			background: yellow;
		}
	</style>
</head>

<body>
	<div class="wrapper">
		<div class="left">左栏</div>
		<div class="middle">中间</div>
		<div class="right">右栏</div>
	</div>
</body>

</html>